Watford manager Malky Mackay faces a selection headache as he is without a host of first-team players.
Left-back Andrew Taylor and midfielder Jordon Mutch have returned to parent clubs Middlesbrough and Birmingham respectively after their successful loan spells ended.
Captain John Eustace is also definitely out with the calf strain which ruled him out of the 2-1 win at Scunthorpe on Bank Holiday Monday to leave Mackay short of midfield numbers.
Top scorer Danny Graham (hamstring) and winger Don Cowie (calf) are touch and go after picking up injuries at Scunthorpe so could miss out.
Midfielder Stephen McGinn remains sidelined with the broken cheekbone and eye socket he sustained against QPR last month and winger Michael Bryan is out as he continues his recovery from a niggling ankle injury.
Tom Aldred, Eddie Oshodi and Nathan Ellington are all back from loan spells with Stockport, Dagenham and Skoda Xanthi respectively but are not expected to feature.
Hartlepool first-team coach Mick Wadsworth is once again without captain Sam Collins.
The defender was injured during the 4-2 win over Oldham on New Year's Day and remains on the sidelines despite his knee problem not being as bad as first feared.
Wadsworth could make changes for the trip to Vicarage Road following his side's 3-0 defeat to Notts County on Monday.
Strike duo Adam Boyd and James Brown are pushing for starts after they occupied the bench in the defeat at Meadow Lane.
Midfielder Antony Sweeney is likely to hold onto his place in the Pools starting line-up following his recent goalscoring form, while Colin Larkin could be recalled.